WO2017013616A1 - Transducer for measuring glucose in blood in a non-invasive manner - Google Patents

Abstract

The invention relates to a system for the non-invasive measurement of blood glucose levels. The system is based on a sensor of the invention. The user presses their finger on said sensor, which is stimulated by means of a radiofrequency sweep generator. The magnitude and phase responses according to the frequency of the reflected wave are measured by an amplitude and phase detector. Said magnitudes are acquired by two analog-to-digital converters of a microcontroller, which, in turn, can transmit the magnitudes to other devices such as, for example, a computer or a smartphone.

Description

 TRANSDUCER FOR GLUCOSE MEASUREMENT IN BLOOD FORM

 NOT INVASIVE

FIELD OF THE INVENTION

 The present invention relates to a transducer that allows the measurement of blood glucose in a non-invasive manner and particularly refers to an integrated device for the measurement of blood glucose in a non-invasive manner.

BACKGROUND OF THE INVENTION

 Diabetes is a chronic condition that is triggered when the body loses its ability to produce enough insulin or use it effectively to keep blood glucose levels within normal ranges. Insulin is a hormone produced by the pancreas that allows the glucose in food to pass into the body's cells, where it is converted into energy for the muscles and tissues to function. As a result, a person with diabetes does not absorb glucose properly, so that it is circulating in the blood (hyperglycemia) and damaging the tissues over time, causing injuries to the eyes, kidneys, nerves, heart disease Stroke These complications can be reduced between 40% and 75% through proper control of blood glucose levels.

Diabetes is a frequent chronic and expensive disease that appears when the pancreas does not produce enough insulin or when the body does not effectively use the insulin it produces. It is one of the four diseases not Priority communicable identified by the World Health Organization (WHO), along with cardiovascular disease (which includes myocardial infarction and stroke), cancer and chronic respiratory disease. It is related to the rapid increase in overweight, obesity and physical inactivity; It has a genetic component and some people are simply more susceptible than others to developing diabetes. Diabetes is at the crisis level and continues to increase. Every seven seconds, someone dies of diabetes, which means that there are four million deaths worldwide each year. In 2012, 347 million people suffered from diabetes and there are another 280 million at high risk of developing it. If nothing is done, the number of people with diabetes will increase to 552 million in 20 years, with another 398 million people at high risk, and by 2030 they could become the seventh worldwide cause of death. Also, 80% of deaths from diabetes are registered in low and middle income countries. In Latin America there are about 15 million people with diabetes mellitus and this figure will reach 20 million in 10 years, much more than expected by the simple population increase. This epidemic behavior is probably due to several factors, among which race, change in lifestyle and population aging stand out. In Argentina, it is estimated that there are two and a half million people with diabetes. The projection for the year 2020 would reach 4 million Argentines.

Today there are numerous devices that allow you to monitor blood glucose levels, but require, in general, a puncture somewhere in the body to draw a blood sample. The invasive nature of conventional methods is painful and usually causes most patients not to perform adequate control. While there are some companies that have dabbled in non-invasive glucometry, there is still no widely adopted technique and its application is currently in an experimental state.

SUMMARY OF THE INVENTION

 It is then an object of the present invention to provide a device for the non-invasive measurement of blood glucose that can be used by the person suffering from diabetes, both type I and type II, to monitor blood glucose levels, and perform a more adequate control of the disease, allowing to accommodate a more adequate diet, and in the case of type I diabetes, to determine in a much better way the application of the necessary insulin dose. The use of such a meter also makes the repeated use of invasive measurements that classically involve puncturing, and the need for test strips, which in general are of high cost.

 It is therefore an object of the present invention to provide a non-invasive system for measuring blood glucose levels. The system is based on a sensor of the invention which represents the finger, which has been designed based on a novel layer model of the human finger. The user must rest his finger on the designed sensor, which is excited by a radio frequency sweep generator. The magnitude and phase responses as a function of the frequency of the reflected wave are measured by an amplitude and phase detector. In the proposed implementation, these quantities are acquired by two of the analog to digital converters of a microcontroller, which in turn has the ability to transmit them to other devices such as: a computer or a smartphone.

Accordingly, it is an object of the present invention a device for the measurement of blood glucose in a non-invasive manner, comprising a blood pressure meter. reflected wave and a sensor, the reflected wave meter comprising a sweep generator based on integrated circuits to synthesize a wave that impacts and is reflected in the sensor; and a bidirectional coupler to receive the reflected wave. .

 In a preferred embodiment of the present invention, the bidirectional coupler generates an output signal that is input to an amplitude and phase detector of the reflected wave which generates corresponding amplitude and phase output signals.

 In a preferred embodiment of the present invention, said sensor is a resonator.

 In a preferred embodiment of the present invention, the operation of the system is controlled by a microcontroller, which controls the sweep of the sweep generator and receives said amplitude and phase output signals from the amplitude and phase detector.

 In a preferred embodiment of the present invention, said microcontroller is in turn connected to an LCD display and / or a wireless transmission module.

DESCRIPTION OF THE DRAWINGS

 For greater clarity and understanding of the object of the present invention, it has been illustrated in several figures, in which it has been represented in one of the preferred embodiments, all by way of example, where:

Figure 1 shows the implementation of the resonator in the device object of the present invention; Figure 2 is an image of the bidirectional coupler used to measure the electromagnetic wave reflected by the device of Figure 1;

 Figure 3 is a block diagram of the complete implementation of the measurement system. The block called "resonator (sensor)" is the device shown in Figure 1, while the bidirectional coupler is presented in Figure 2.

 Figure 4 illustrates the test bench used to analyze the performance of the resonator of the invention.

 Figure 5 shows the model of the human finger used to design and simulate the resonator presented in Figure 1.

 DETAILED DESCRIPTION OF THE EMBODIMENT OF EMBODIMENT

The equipment consists of a reflected wave meter, and a sensor of the invention.

 This requires a sweep generator to synthesize the wave that will affect the sensor. This sweep generator for the functional prototype will be based on the ADF4351 integrated circuit of Analog Devices. Then, a bidirectional coupler (also developed exclusively for this application) will be used.

The complete meter also involves the preliminary design of a frequency sweep up to 2.8 GHz, a reflectometer for measuring the input reflection parameter of the resonator-finger system, based on the design of a bidirectional coupler. The implementation of an ultrasonic thickness gauge that has been used to more accurately determine the thicknesses of the layers of human tissue that are part of the model of the human finger used is also postulated. The The output signal of the bidirectional coupler is input to an amplitude and phase detector of the reflected wave.

 Although the level of blood glucose is currently estimated based on measurements of the amplitude of the reflected wave, there are studies that indicate that there could also be information of interest in the phase of the reflected wave, which is why we plan to continue with the investigation, the integrated circuit AD8302 of Analog Devices that allows to detect these two magnitudes in the frequency range of interest was used.

 The operation of the system will be controlled by a microcontroller (in the implementation carried out one of the Microchip firm was used), this will be responsible for controlling the scanning of the ADF4351 and receiving the amplitude and phase signals from the AD8302. In addition, this will be used as an interface for the user, since it will have external controls, a liquid crystal display or LCD display to present the results obtained and in one of its serial ports a Bluetooth link or a wireless transmission module that It will allow you to communicate with a computer or a smartphone.

The measurement bank used consists of an HP8594 E Spectra Analyzer that also has a frequency sweep generator that reaches 2.9 GHz. This signal is used as an incident wave to the resonator-finger system, which acts as a load connected through an HP 778d bidirectional coupler, from which the reflected wave arises, which is connected to the spectra analyzer input to observe its variation with respect to the frequency, and thus be able to determine the resonance frequency it presents. In the experiment measurement procedure, the individual ingests some type of high glycemic food to raise blood sugar levels. The experienced case individual is a healthy individual, who does not He suffers from diabetes, and for whom the plastic support for fixing the little finger posture was custom built. At 5 minute intervals, the frequency response measurements were made and at the same time the glucose values were determined by means of a conventional invasive meter. Taking into account that conventional invasive meters determine blood glucose levels with an error of + - 10%, the measurements resulted in a linear correlation between resonance frequency and glucose values, for the individual subject to the measurement.

 The design method is based on electromagnetic simulation using computer programs, and in this simulation of the finger-resonator system, the electrical model of the human finger is critical, which is represented by a layer model, which simulates the electrical characteristics of the different tissues, epidermis, dermis, muscle, fat, blood and bone. To carry out this model, initially some classical parameters obtained from the literature were used, but then it was discovered that the current finger model should be improved, given the fact of the discrepancies found between computer simulation and experimental measurements. In this process of improving the model, the dimensions of the layers of the model were determined from ultrasound of the human finger, with the help of a professional. To establish the dielectric properties of each layer, the Debye model was used, widely used to characterize biological tissues or any other sample that exhibits dispersive nature in its intrinsic electrical properties.

Once the living tissue is modeled, a thorough study of the planar structures used in microwaves is carried out to evaluate which structure is the most appropriate. In this case, three different technologies were studied: microstrip structures, coplanar structures and coplanar structures with mass plane. Due to the inhomogeneous nature of the sample and the variability between individuals, the sensitivity to not only changes in blood glucose, but also the invariance to parameters such as skin thickness, finger size, was taken into account. etc. As a result of the analysis it is concluded that the technology to be implemented is a coplanar sensor with mass plane. It was implemented in practice, and in the actual implementation a support built in plastic was added to guarantee a certain degree of repeatability in the measurements made as to how to position the finger on the transducer.

 The measurements were satisfactory, being able to corroborate the simulations carried out and check the correlation between the sensor response and the blood glucose level of the sample, a principle that gave rise to this invention. There is also a high dependence on associated factors, which leads to a dependence on the measurement with respect to the characteristics of each individual, which appears as a problem to be solved.

 Referring to Figure 5, each of the materials that make up the finger model and its corresponding thicknesses is presented. These thicknesses are not those used in the literature, but were obtained through the corresponding clinical studies.

Claims

 1. A device for non-invasively measuring blood glucose, comprising a reflected wave meter and a sensor, the reflected wave meter comprising a scanning generator based on integrated circuits to synthesize a wave that impacts and is reflected on the sensor; and a bidirectional coupler to receive the reflected wave. . 2. The device according to claim 1, wherein the bidirectional coupler generates an output signal that is input to an amplitude and phase detector of the reflected wave which generates corresponding amplitude and phase output signals. 3. The device according to claim 1, wherein said sensor is a resonator. 4. The device according to claim 2, wherein the operation of the system is controlled by a microcontroller, which controls the sweep of the sweep generator and receives said amplitude and phase output signals from the amplitude and phase detector. 5. The device according to claim 4, wherein said microcontroller is in turn connected to an LCD display and / or a wireless transmission module.